On Python 3, dict.keys() doesn't return a list, so we can't sort it, but
converting to a list on the fly before calling to sort() is not going to
change the original dict_keys object. Storing directly the list in the
variable, we get the expected result.
Side note: the daylist2 variable is there just for the t-set and was
already present in the code. Renaming it to dummy would be clearer
but that should not be done in stable.
Closes#25113.
Pedro M. Baeza
1bf483b047